Congo Photo Gallery: Expedition BonoboThe only jungle dwellers more mysterious than the Iyaelima people are the rare bonobo apes that live alongside them. A perilous expedition into the Democratic Republic of the Congo hopes to establish contact that will help preserve them both.Photograph by Robert J. Ross

During the course of our trek through Salonga National Park, we walked more than 100 miles (160 kilometers). Jo, who is just over 50 years old, was remarkably fit and agile. When crossing streams or rivers on slippery log bridges, she'd accept a helping hand, but her lavendar Crocs (that she wore for the entire trip) stood her well. —Photographer Robert J. Ross